Aircraft fuel contamination either from water or particulates can interrupt fuel flow leading to catastrophic engine failure. Particulates and ice can plug fuel filters, and slugs of free water can cause engine flameout. Despite careful design of equipment and procedures, technician training and supervision, engine failures still occur resulting in degraded mission effectiveness, damaged equipment, and loss of life. Progeny Systems proposes Aviation Fuel Contaminant Cutoff (AFCC) as an innovative approach for automated particulate and free water fuel contaminate monitoring and fuel cutoff. AFCC continually monitors the fuel stream, senses contamination, and when appropriate stops fuel flow to prevent contaminant introduction into the aircraft. A self-contained modular adapter, AFCC is rugged, compact, low-power, and affordable, and can be easily integrated with existing refueling systems without any special operator training or extensive field maintenance requirements. AFCC uses piezoelectric scattering ultrasound to probe the entire unimpeded fuel flow in real time to detect both particulate and free water contaminates. A supplemental optic sensor allows for continuity of operations should entrained gas be present in the fuel. A zero differential pressure solenoid cutoff valve shuts down fuel flow should contaminants be detected.